started work on composite pattern

pypatterns/structural/composite.py

@@ -0,0 +1,63 @@
+
+
+class Composite(object):
+    """
+    Composite class as part of the Composite pattern.
+    """
+    def __init__(self, interface):
+        """
+        Initialize a new Composite instance.
+        """
+        self.components = set()
+        self.interface = interface
+        self._method_names = [method for method in dir(interface) if callable(getattr(interface, method))]
+
+    def add_component(self, component):
+        """
+        Add a component to this composite.
+
+        @param component: The component to add to this Composite
+        """
+        component_methods = [method for method in dir(component) if callable(getattr(component, method))]
+        for method_name in self._method_names:
+            if method_name in component_methods:
+                continue
+            else:
+                raise AttributeError
+        else:
+            self.components.add(component)
+
+    def remove_component(self, component):
+        """
+        Remove a component from this composite.
+
+        @param component: The component to remove from this Composite.
+        """
+        try:
+            self.components.remove(component)
+        except KeyError:
+            pass
+
+    def delegate(self, func_name):
+        """
+        Apply a function to all child components by function name.
+
+        @param func_name: The name of the function to call with all child components.
+        @type func_name: str
+        """
+        for component in self.components:
+            attribute = getattr(component, func_name)
+            if callable(attribute):
+                attribute()
+            else:
+                raise AttributeError()
+
+    def __getattr__(self, item):
+        """
+        Override getattr to delegate all function calls to children.
+
+        @param item: The function to call with this composites children components.
+        @type item: str
+        @return: A function that when called will call all child functions with the given function name.
+        """
+        return lambda: self.delegate(item)